Xtal Set Society, Inc. Updated 08-06-14
The capacitors pictured above, from left, include our 365 pf dual-gang variable, our 365 pf variable with 8:1 shaft reduction drive, a 365 with shaft extended with nylon parts, and a 365 attached to a 6:1 external planetary reduction drive. A bracket to mount the planetary drive is shown below, RD2. For more details on these parts, see the capacitor-lineup-mounting page.
For Nylon Mounting parts, see the nylon parts page.
All other current parts offered are listed in the parts catalog below.
MK484 TRF Radio Chip in TO-92 Pack
LM386-4 Audio IC in 8-pin DIP new 07/20/14
2N5486 JFET in TO-92 IC new 07/20/14
Brass Binder Posts & Detector Parts
Capacitor, 365 air variable
** & mounting bracket for**
Spacer for 365 air variable
Capacitor, 365 air variable with 8:1 reduction drive,
Capacitor, Dual Gang air variable
Planetary Reduction Drive, 6:1
** with optional mounting bracket and pointer**
Catwhisker, Phospher Bronze
Coil Forms, PVC
Coil Form, Spider Web/Spiral new 11/26/13
Ear Plugs, Crystal
Ferrite Toroids and Rods
Panels and Dials
Potentiometers, panel mount
Transformer: 1200-to-8 ohm
Wire: hookup, magnet & Litz
MK-484 TRF AM RADIO Chip in TO-92 Pack
The MK484 is an offshoot of the famous Ferranti ZN-414 and is a tuned radio frequency (TRF) radio in a small TO-92 transistor-like package. Combined with (these parts not included) three resistors, three capacitors, an ear phone, 1.5V battery, tuning coil and tuning capacitor, you can make an AM receiver for the AM band and up to 3 MHz. See our article in the July issue of our newsletter for a circuit example with details. Suggested schematic and parts list sent with each IC (chip). See Cat # XSMK. $2.49 each.
LM386-4 Audio IC in 8-PIN DIP
This IC is ideal for many audio projects and great for buffering between a crystal set and pair of modern day 8-ohm headphones. The gain can be adjusted by using a pot at the input, usually 10K. The output drives an 8-ohm load, See Cat # XS386. $1.95 each.
2N5486 JFET - FIELD EFFECT TRANSISTOR IN TO-92 PACKAGE
The transistor is used in our JFET and Infinite Impedance Detector kits and is ideal for buffering between a crystal set tuned circuit and an audio load with such as a pair of headphones. Pinouts are shown on the picture at right. G is the gate pin, S is the source pin and D is the drain pin. See Cat # XSJFET. $1.95 each.
Alligator Clip Five Pack
This "five" pack includes five alligator clips. each 2 inches in length. As per the picture, each clip has a screw terminal for attaching a wire. Ideal for clipping leads to coils or making up jumper cables.
Binder Post, Brass
Small brass connector post similar to those used in early radios. Includes custom threaded 0.15 inch diameter base screw and thumb wheel top for tightening wire. Wire opening is 0.1 inch and accommodates old style headphone plug terminals.
The picture below displays additional brass parts and a compression spring. These parts are used in our Galena Detector Kit and are useful for other projects too. The 1.5 inch free-length, 0.3 dia spring is shown at left. A 0.375-inch 6-32 taped brass ball is second to left. These two parts can be mounted on the 2.5-inch threaded rod noted above. The rod we stock is brass. The next item is the brass cup, which accepts our Mounted Galena (see further down the parts page). The cup contains two 4-40 holes for mounting and securing the Mounted Galena. The L-Bracket, two of which can be used to hold the rod and ball in a detector assembly, is shown at right. (see the Galena Detector Kit picture).
Connector Assortment : You can use the connectors shown in the picture in your next project. The assortment includes: 6, 6-32x3/8 inch Phillips-head screws;
6, 6-32x1/4 screws;
12, 6-32 hex nuts;
6, 4-40x3/8 screws;
6, 4-40 by 1/4 screws;
12, 4-40 hex nuts;
6, #6 solder lugs;
2, 1-inch x1/2 nylon rod;
2, 1.5 inch x1/4 nylon rod. Examples: you can use a screw, solder lug, and nut to provide for a connection to the frame of one of the air variable capacitors listed below. You can use the two nylon parts and two 4-40 x1/4 screws to form a shaft extender for a variable capacitor as shown in the second picture to the right.
Capacitor, 365 air variable
As the surplus for 365pf caps has dried up, these little beauties were getting harder and harder to find. Not anymore! The Society now has a plentiful supply; we have them manufactured. They are brand new caps, 31 blade, .010-air-gap, 1/4" tuning shaft, and CW rotation decreases capacitance. Testing indicates a capacity range of ~~ 390 (fully meshed) to 16 pf (fully open). Shaft accommodates the pointer knob shown (sold separately - see this page), and a reduction drive for slower tuning (also sold separately - see this page).
Connections. The frame of the capacitor is connected to the rotor plates and electrical connection must be via a solder lug (or other arrangement) with a 6-32 screw in the bottom, front, or back of the frame. (The 1920s units were this way!). The fixed plates connect to either of two solder lugs installed in the little brown phenolic boards on each side.
The cap can be panel mounted from the front or on its base via pre-taped 6-32 holes. The flat spacer shown in the top picture (and sold separately) enhances mounting the cap via its base. Without a spacer (shim) , the phenolic connector boards at each side may be broken when tightening the mounting screws. The spacer fits between the phenolic (pcb) legs and matches up with the holes in the bottom of the cap. Machine screws must be 6-32 by 3/8ths or ¼-inch, depending upon the thickness of the mounting surface. (Screws are not provided. See the "Connector Assortment above.)
If you desire to mount the cap above the chassis platform and away from the front panel, the Vertical 365 Mounting bracket, shown at right in picture 2 is also offered. Holes at the bottom of this L-shaped bracket can be used to mount to the chassis; and, the two small vertical slots are provided
for 6-32 by 1/4 screws to secure the cap to the bracket. Adjust height as desired. Please note that the dimensions of this 365 Vertical Bracket are NOT the same as those for the Reduction Drive bracket.
For more detail on installing/mounting these parts, click here.
Capacitor, 365 air variable with 8:1 reduction drive shaft
This variable cap is exactly like our 365 listed above but includes an 8:1 reduction drive, embedded in the shaft. It's part number is 365-8-1.
What's a reduction drive? It's a mechanical device wherein the plates of the capacitor turn at a slower rate than the attached knob. With this assembly it takes four rotations of the knob to turn the 365 cap from max to min capacitance. Thus a very small change in capacitance is easier to tune/achieve.
Electrical Connections. The frame of the capacitor is connected to the rotor plates and electrical connection must be via a solder lug (or other arrangement) with a 6-32 screw in the bottom or side of the frame. Solder lugs connect to the stator via the brown phenolic plates. The spacer listed above fits the 365-8-1 too.
Capacitor, Dual Gang air variable
The 1/4-inch shaft rotates both sections of rotary plates simultaneously, and each is grounded to the general case - and is thus a common connection point via the frame with screws/lugs. Each section of stationary plates is isolated and has separate solder lugs and mica trimmers. Mounting is with 6-32 machine screws via dimpled standoff holes on the bottom of the chassis.
Planetary Reduction Drive, 6:1
This add-on reduction drive rotates the shaft of an attached device - such as our 365 capacitor - at 1/6-th the turning rate of the front panel knob. The shaft of the driven device is secured by set-screws in the enlarged output shaft of the drive, and the drive is mounted with an L-bracket via the two "wings" as shown in the picture. The input shaft accommodates a 1/4-inch knob.
This drive can be combined with our 365-8-1 capacitor for a gigantic reduction in cap plate rotation of 48:1!
Pointer Add On for the Planetary Reduction Drive
The pointer is shown at left in the picture to the right. The large hole slips over the knob shaft of the reduction drive (shown attached to an L-bracket at right)
and is secured with a 2-56 screw (provided with the pointer). A tapped hole is provided on the the disc surface of the drive to accept the screw. Works ideally as a pointer mounted on a reduction drive and displayed through a windowed panel.
See an example of a windowed panel in the Panels and Dials section listed below.
Mounting Bracket for the Planetary Reduction Drive
As per requests from the membership, we have modified the mounting bracket for the RD 6-1 reduction drive to mate with the 365 dual-gang cap as well as with the 365 and 365 8:1caps. As noted in the picture, the “RD2 Bracket” is L-shaped, secures at the base with 4-40 or 6-32 hardware, and attaches to the reduction drive with 4-40 nuts and machine screws. (The nuts and screws are not provided.) The large opening in the center accommodates the large shaft of the drive, which in turn slips over a ¼-inch tuning shaft of the XSS-365 capacitors or other components such as panel mount pots. For the RD2 Bracket to fit with the XSS-365 capacitor, it is assumed that the 0.060-inch capacitor mounting "spacer," or two solder lugs are placed under the cap. (See the XSS-365).
For more detail on installing/mounting the reduction drive with the bracket, click here.Please note that the dimensions of this bracket are NOT the same as those for the 365 Vertical bracket.
||Label on Part
This ceramic cap assorment includes two each of caps commonly found in crystal sets, as per the table. A sheet on how to identify labeling on the capacitors comes with the assortment.
Catwhisker, Phospher Bronze
Small wire with wound springy end for "catwhisker" replacement in a detector stand. Generally one screws the wound (springy) portion of the whisker onto a threaded shaft. The other end is pressed against a mineral, such as galena.
Coil Form: Spider Web (Spiral)
We're pleased to announce our new SPIDER COIL FORM. This 5 by 6 by 1/8th inch low-loss ABS plastic form includes nine NC punched radial slots and five mounting holes. The inner diameter is 1.6 inches and the outer diameter extends to the edge of the form, 5.0 inches. This size supports 250 uH coils (good for the AM band) when used with #22 or #26 enamel, or 150/45 Litz wire. Weight of the form itself is 2 oz. For example, a coil consisting of 56 turns of 150/45 Litz, with a 1.6 inner diameter produces a 4.2 inch outer diameter.
An instruction sheet is included with the form, showing how to wind the coil and how to calculate inductance given the size of the wire, the number of turns, and the inside and outside radiuses of the spiral coil.
Click here to download a pdf file on the spider coil formula or go to the formulas-calculators page on this web site.
#22 and #26 enamel and 150/45 Litz wire are sold separately on this catalog page.
Coil Forms: Cylindrical and Toroidal
The PVC & ABS plastic pipe forms - cylindrical - are pre-cut and pre-drilled, ready for you to wind coils. Each kit contains 3 pipes, 6@ 6-32 metal screws and 6 nuts, and a coil information sheet. You may wish to use nylon (non-conducting) nuts & bolts to install the forms in a set. See Nylon-Parts. Also see the Coil Calculator to determine number of turns for a target inductance. As with wood, actual diameter of pipe is not the same as that called out or printed on the pipe. Physical outside diameter and length for each form is listed below.
The Toroidal Coil form kit includes two FT-82-61 ferrite toroids with nylon washers and nylon machine screws/bolts for mounting and instructions for winding enamel wire. These ferrites are ideal for the AM Broadcast Band. We recommend #26 magnet wire, not included. To order toroids and rods, see the "ferrite toroids & rods" section on this web page.
|PVC 3/4 inch
|PVC 1 inch
Diodes, 1N34: The 1N34 has radial leads and a glass housing. Dark ring on one end denotes the "negative" side.
High impedance crystal earphone with tinned ends. Use in place of old-style hi-impedance headphones. Place a 47K or greater resistor across the earplug leads.
Fahnestock clips: Used to connect antenna, earplug, or phones to a set. Fits 6-32 nut and screw (not provided).
We offer galena crystals in a 0.475 inch diameter woods metal mounting or raw. Each mounted crystal has been tested. The mounting fits nicely in many old style detector stands. Crumpled aluminum foil and a wire jammed into a hole can offer an alternative way of mounting.
Packs include 4 molded RF chokes (that look like resistors), suitable as coil substitutes for making miniature crystal sets. Just think; you can make crystal sets without winding a single coil. Q will be somewhat less than when using wire wound coils. Packs include a sheet on several possible projects to build. The L-Pack includes one each as in the table. The 250-pack includes 2 33 uH and 2 250 uH molded coils.
Knob, Pointer: This knob fits on a ¼-inch shaft; hence, it fits our 365 single and dual gang air capacitors and panel mount pots. Set screw in knob secures knob to shaft. The knob is shown in the picture with the 365 air variable capacitor above.
Panels and Dials: Round Dial Plate, Shaft Dial Coupler, Dial Pointer & Front Dial Panel
The dial plate is 2.4 inches in dia., 0.04 inches thick, has a 0.340 inch center hole to accommodate the outer shaft of our 6-1 vernier drive and four mounting holes to accommodate 2-56 by 1/8th screws to mate with the threaded holes on the 6-1 drive.
The front panel is 2 x 4 x 0.05 inches, black anodized front and back and includes lazered graphics on the front in white. A semicircular cutout accommodates view of the dial pate mounted behind the panel. Four corner holes allow for panel mounting.
A dial coupler for our 365 air variable capacitor (without internal vernier drive) is shown at upper right. It's 0.87 inches in dia. 0.18 inches thick with a 0.25 center hole to accommodate the capacitor shaft. Two tapped 2-56 holes on the face match the mounting holes on the dial plate. Two tapped 4-40 holes on the on the side are provided to secure the coupler to a quarter inch shaft; and, one can be used to accommodate the dial pointer pictured just below it.
For more detail, download the new mechanics pdf here.
Potentiometers, panel mount
These potentiometers are ideal for front panel installation. Both log and linear taper 10K, 100K, and 1MEG pots are now stocked. Log taper are ideal for audio volume control and linear taper are useful for diode bias or a Benny, amoung other apps. Pots include three solder lug terminals, 0.25" dia by 0.5" (in front of panel) shaft with threaded base, tit, and nut for mounting, and fit our pointer knob too!
Resistor, 47K: This 1/4-watt resistor is sued with our earplug in a number of kits, including the Oat Box Kit.
Solder Lugs: Useful for may connections, including chassis ground. Mounts with 6-32 nuts and screws (not included).
Toroids: FT-82-61 and FT-87A-J ... plus Ferrite Rod: R61-50-300
Ferrite toroids are often used as a form for winding a coil, enabling a large inductance in a small space. The FT-82-61 is suitable for the AM broadcast band and hence for crystal sets. The FT-87A-J is useful for audio and ultrasound filters. The equation for the number of turns varies for different sizes, shapes and types of ferrite materials.
For a desired inductance with these toroids, the number of turns required is calculated as follows:
For the FT-82-61, N (# turns) = 1000*SQRT(L(in mH)/73.3). Hence 58 turns provides for an inductance (L) of 250 uH. For the FT-87A-J, N (# turns) = 1000*SQRT(L(n mH)/6040).
For the R61-50-300 ferrite rod, N(# turns) = 1000*SQRT(L(in mH)/43). For best Q, the windings should be centered on and cover a majority of the length of the rod. This rod has a 1/2 inch diameter and is 3 inches in length. See our medium clamp on the nylon parts page for mounting.
Toroidal coils can be mounted using glue or nylon washers and screws, not included.
We also sell the FT-82-61 toroid in a TWO PACK KIT, including nylon hardware, as noted in the picture at right. The toroid is mounted between two large 1.25 inch nylon washers, which in turn are secured by a nylon hex nut. The bolt is 2.5 inches long, enabling you to stand the toroid 1.5 inches above the mounting surface with the remaining two nuts. The coil leads then drape down and are attached to whatever.
Transformer: 1200-to-8 ohm
This transformer is useful as part of a matching network for a crystal set to 8-ohm headset or speaker.
Primary is 1200 ohms; secondary is 8 ohms. Application sheet included. For sensitive (DX) sets, one must use an intermediate transformer between the set and this transformer. For beginner sets, try tapping the detector diode part way down the set coil and interconnect the other end of the diode to the primary of this transformer. An 8-ohm headset would then be attached to the secondary 8-ohm output.
Wire: hookup, magnet & Litz: Coils can be wound with hookup, magnet, or Litz wire. See the January 2008 issue of the Xtal Set Society Newsletter for an introduction to the use of Litz (or woven) wire. Wire diameter and covering are listed in the table.
|#24 AWG hookup
|#26 AWG magnet
|#22 AWG magnet
|150/46 Served Litz
||0.024 inch bundle